This invention relates generally to semi-truck air conditioning systems, and more particularly to an integrated air conditioning system which is selectively operable by either the main engine or an auxiliary power plant which can drive the compressor when the primary engine is not operating.
Semi-truck tractor trailers frequently employ the use of an auxiliary generator to meet electrical requirements when the main engine is not running. Tractor trailers having a xe2x80x9cbunkxe2x80x9d or xe2x80x9csleeperxe2x80x9d cab area are common and most interstate fuel stations permit the drivers of such vehicles to sleep in their cab. The passenger area of the truck may include convenience items such as a television, VCR, refrigerator, air conditioner, coffee maker, even a microwave oven. While such items may run on direct current provided by an engine mounted alternator, or even alternating current by use of an inverter, the truck engine must be running. Idling laws now prohibit the running of the main engine for prolong periods of time. However, the time and cost savings of keeping the driver near the vehicle while at rest are obvious and ancillary benefits include security as the operator does not leave the vehicle unattended. A problem with the use of auxiliary generators is directed to size, weight, and placement. The size of an auxiliary generator is critical for if the overall dimensions are too large, there will be insufficient areas on a truck for which to place the auxiliary generator. For instance, it is not practical to place an auxiliary engine within the existing main engine compartment. Placement of an auxiliary engine on the frame rails is a known alternative, however conventional auxiliary generators employ baseplates making the size, weight, and subsequent placement a problem.
The use of gasoline engines to power a generator is also well known. Gasoline engines are lighter in weight and smaller in size when compared to a diesel engine of the same horsepower. However, gasoline is a very volatile fuel and when a gasoline engine is placed into the confines of a container or step box, the gasoline engine must be made either xe2x80x9cspark proofxe2x80x9d or it will present a lethal environment that can create an explosion. Further, when used on a diesel powered tractor trailer, a separate fuel tank is required and grounding becomes critical since any stray spark can ignite gasoline. An example of a system using a gasoline engine is seen in U.S. Pat. No. 3,844,130 which discloses an auxiliary power system for a automobile air conditioner which utilizes an electrical generator and gasoline engine located in the trunk of the automobile.
The Applicant is a well known assembler of diesel engine/generators packages and has been awarded patents for various arrangements. U.S. Pat. Nos. 6,047,942 and 5,765,805 to the Applicant disclose the use of a combination engine/generator that is lightweight and of a novel space saving configuration. The contents of U.S. Pat. Nos. 6,047,942 and 5,765,805 are incorporated herein by reference.
The prior art discloses numerous systems by which air conditioning and heating can be provided in a motor vehicle while the engine is not running. Some systems, such as that disclosed in U.S. Pat. Nos. 4,756,359, and 4,762,170, utilize separate and wholly independent auxiliary air conditioning systems which are powered by auxiliary power plants. In terms of economy of both expense and space, it would be far more desirable to provide a system which utilizes the existing standard air conditioning system of a vehicle instead of providing dual systems. An example of this can be seen in Diefenthaler, Jr., U.S. Pat. No. 4,531,379, which teaches use of a auxiliary engine located in the engine compartment which serves to drive the air conditioner compressor when the main engine is not running. A clear disadvantage of the Diefenthaler, Jr. system is the inherent difficulty of placing a second engine in the engine compartment due to space considerations. Also, the Diefenthaler, Jr. system would not be suitable for a xe2x80x9cretrofitxe2x80x9d installation.
Thus, what is needed is a means to drive the existing, standard air conditioning system in a semi-truck without the main engine running which makes an economical use of space can be readily integrated into the air conditioning system.
Accordingly, it is an objective of the instant invention to provide an integrated air conditioning system which is selectively operable by either the main engine or an auxiliary power plant which can drive the compressor when the primary engine is not operating.
It is another objective of the invention to provide an integrated vehicle air conditioning system which utilizes an electric motor coupled to the drive shaft of the compressor of the existing air conditioning system in order to operate the air conditioning system when the main engine is not running.
It is a further objective of the invention to provide an integrated vehicle air conditioning system which includes an auxiliary power plant to drive the electric motor.
It is yet another objective of the invention to provide an integrated vehicle air conditioning system to retro-fit on existing vehicles.
In accordance with the above objectives, an integrated conventional air conditioning system for use in trucks which is selectively operable by the main engine or an auxiliary power plant is provided. The integrated conventional air conditioning system consists of an air conditioner compressor having a single shaft with a clutch engagable pulley coupled thereto and a belt-driven pulley mounted thereon. The clutch engagable pulley is rotatable by the main engine and the pulley is operable to drive the shaft independently of the clutch engagable pulley when the main engine is not operating.
An electric motor is mounted to and mechanically linked to the air conditioner compressor. The electric motor has a second clutch engagable pulley operatively coupled thereto wherein the second clutch engagable pulley is rotatable when the electric motor is operating. The second clutch engagable pulley is coupled to the belt-driven pulley mounted on the shaft. A means is provided for selectively and independently engaging the first clutch engagable pulley and the second clutch engagable pulley for operation of the air conditioner compressor, whereby the conventional air conditioning system introduces cool air through the truck mounted air conditioning ducts while the main engine is operating or when the auxiliary power source is employed. An auxiliary power plant provides power to the he electric motor.
The auxiliary power plant includes a horizontally disposed one cylinder liquid cooled Kubota diesel engine integrally coupled with a low profile auxiliary generator. The generator is preferably an alternating current generator. The auxiliary power plant provides about 3.5 kilowatts. The auxiliary power plant is fixedly placed within an enclosure having an interconnected floor, opposite vertical side walls, opposite vertical end walls, and a top parallel to the floor. The Kubota diesel engine is rigidly connected to the electrical generator by a thin vertical planar bracket. The engine has at least one cylinder disposed parallel to the floor for turning the generator to produce electricity. To reduce vibration, the auxiliary power plant is connected to isolation mounts which are fixed to the floor of the enclosure. The height of the vertical end walls and the vertical side walls of the enclosure is approximately 15 inches.
The liquid cooled engine has a remotely mounted radiator and associated fan. The radiator is located between the perforated wall and the associated fan whereby the fan extracts heat from the enclosure and provides air flow across the radiator.
The integrated conventional air conditioning system is used with an auxiliary power source wherein the means for selectively and independently engaging the first clutch and second clutches includes a relay means for preventing simultaneous operation.